For a great many years it has been known to force curved blades into the earth around a tree to be moved to isolate its root structures and the surrounding earth into a roughly semi-circular tree ball that can be lifted from the ground and moved to the desired new location for the tree and reinserted in a prepared hole in the ground. See the patent to Wilkens, U.S. Pat. No. 594,668, granted in Nov. of 1897.
It is also well known to provide hoops to serve as guides for the tree digging staves which are to be pushed into the ground, and to have these hoops split so that they can be assembled around the tree. See the patent to Sager, U.S. Pat. No. 1,599,841, granted in Sept. of 1926. To utilize the device of the Sager patent, each of the staves or digging blades had to be pounded into the ground manually.
It is known to utilize racks and gears to force cutting blades or flat digging spoons down into the ground in a tree balling device. See the patent to Wassell et al, U.S. Pat. No. 2,769,278, granted in Nov. of 1956. In this structure, the rack must extend down to the lower edge of the cutting blade and thus the rack offers substantial resistance to being forced into the ground.
It is well known to use hydraulic piston-cylinder linear motors to drive digging blades into the ground and to pull them out again. See the patent to Bates, U.S. Pat. No. 3,618,234, granted in Nov. of 1971.
It is also well known to utilize hydraulic powered lifting devices to lift tree moving assemblies, trees, and tree balls to tilt them to a convenient position for transportation, to transport them on a vehicle and then to tilt them and lower them to place the tree in an opening previously prepared. See the previously mentioned patent to Bates, and the patent to Crawford, U.S. Pat. No. 2,990,630, granted in July of 1961.
In these days of high labor costs, however, it is necessary or at least very highly desirable to provide a tree transplanting machine which is entirely power operated, and which machine, together with the vehicle to which it is attached, can be operated by one man.
In order to get underneath the branches of a large tree having low branches, without injuring or removing those branches, it is necessary that the vertical above-ground clearance of the machinery which must encompass the tree trunk be kept just as low as possible. In the prior art structures, typically, the ratio of movement of the hydraulic cylinder piston motor to that of the digging blades had been one-to-one. See the previously mentioned patent to Bates. In some structures of the prior art, in order to gain more power, a reverse ratio has been used whereby the movement of the blades into the ground is only one-half of that of the movement of the power means forcing the blades into the ground. See the patent to Sigler et al, U.S. Pat. No. 3,017,719, granted in Jan. of 1962.
In structures such as shown in the aforementioned patent to Bates, the digging blades are straight in longitudinal dimension and must be forced into position by upwardly extending straight hydraulic motors. To handle trees of large sizes, this necessarily results in a structure which is too wide to be carried down the highway.
To minimize the resistance to the digging action as each of the digging spoons is forced down into the ground, it is important that the spoons be kept as clear of the machinery as possible and that a very minimum of the machinery parts be forced down into the ground. It is equally important that any such parts are self-cleaning in nature so that they will not clog up the workings of the machine when they are taken back out of the ground by use of the power means.
To overcome difficulties with the prior art structures and to provide an improved tree transplanting machine, the present invention was developed.